Multi-chamber containers are used for a number of products. The primary use is where a product is comprised of two or more incompatible components. These components must be kept separate until the time of use. At that time they can be mixed and used. The incompatibility can be the result of a fast or slow reaction between components. As an example oxidants and reducing agents must be kept separated. Likewise acids and bases must be kept separated. Consumer products where components must be kept separated include hair dye and bleaching products and some dentifrice such as high fluoride formulations, densitizing formulations, baking soda/peroxide formulations and peroxide tooth whitening formulations. A problem that can arise in the dispensing of multi-component formulations from multi-chamber containers and how to get the desired amount to flow from each chamber, This can be equal amounts from each chamber, or differing amounts depending on the product and the components.
A multi-chamber container that is used for some hair coloring products and for some dentifrices is the dual chamber tube. These can be side by side dual chamber tubes as described in U.S. Pat. Nos. 1,894,115; 3,758,520 and 3,980,222 or concentric tubes as described in U.S. Pat. Nos. 1,535,529; 1,639,699 and 1,699,532. The problem of dispensing desired amounts from each chamber of a dual chamber tube has been addressed in U.S. patent applications U.S. 2003/0106903 and U.S. 2003/0106905. The technique in these patent applications is to place a flow controller in the shoulder of the tube. This may can be effective in some instances but is of a complex construction and difficult to adjust for dispensing the substance in varying ratios.
The problem is solved for dual chamber tubes by placing a flow modifying unit in the nozzle of the tube. This facilitates the construction of the flow modifying unit and provides an efficient way to be able to adjust the flow ratio from each chamber. Also by placing the flow modifying unit in the nozzle there can be better control of the suckback of product from the nozzle back down into the tube chamber. Further there is an advantage in that the flow modifying unit can be produced at the time that the nozzle is made through the use of specially designed mold pins.